The present invention relates to devices, systems, and methods for powering modern electronic equipment, such as microprocessors and, more particularly, to devices, systems, and methods for providing high current at low voltage to modern electronic equipment using multi-phase, interleaved power supplies.
Conventionally, a common approach to powering modern electronic equipment with high current, e.g., greater than 100 amperes (A), at low voltage, e.g., about 1 Volt (V), is to combine in parallel several DC-DC converter channels, or phases, to provide a multi-phase, interleaved power supply. This can be done for DC-DC buck converters as well as for DC-DC boost converters.
The common, multi-phase, interleaved approach distributes loading between multiple components, achieving an efficiency that is otherwise not achievable with a single-phase approach. Using multiple, smaller components rather than a single, larger component may also be desirable as a function of available space.
Disadvantageously, due to transients, load currents for modern microprocessors are characterized by a high rate of value change, which necessitates using filtering inductance devices having smaller rather than larger value inductors. Small value inductors, however, increase output current ripple, which magnifies losses and reduces conversion efficiency.
U.S. Pat. No. 6,362,986 discloses means and methods for coupling inductance devices to moderate an increase of ripple in inductance devices and switching devices caused by using small value inductors. For example, referring to FIG. 1, there is shown a two-phase DC-DC power supply 10 having two (N=2) power sources 17 and 19 that are adapted to be 360°/N, or 180°, out-of-phase.
The power supply 10 includes an inductive filter 12 for moderating the ripple increase. The inductive filter 12 has electrically-conductive windings 14 and 16 that are wound in like orientation about rungs 11 and 13, respectively, of a magnetic core “ladder” 15. Typically, there is one winding 14 or 16 for each phase of conversion.
Winding 14 is electrically coupled to a first pulsed power source 17 having a first phase through a switching device (not shown). Winding 16 is electrically coupled to a second pulsed power source 19 180° out-of-phase to the first phase through a switching device (not shown). As current is driven through the windings 14 and 16, magnetic flux is produced. The magnetic flux travels outside and around the magnetic core 15, inducing current to flow through the magnetic core 15. The magnitude and direction of flow of the induced current in the magnetic core 15 depends on the magnitude and polarity of the current in each of the windings 14 and 16.
Switching devices (not shown) are adapted and controlled to activate (energize) and de-activate (de-energize) the windings 14 and 16 to provide the desired result. Thus, the switching devices can be used to cross-couple the windings 14 and 16.
Cross-coupling between windings 14 and 16 causes or prevents interaction between the discrete fluxes and the induced currents generated by each of the windings 14 and 16. Hence, by selectively cross-coupling the fluxes and currents during power supply operation from multiple power sources 17 and 19, phased current ripple associated with the output current can be reduced.
One problem associated with such an arrangement, however, is that the effects and results of cross-coupling between windings that are not immediately adjacent to one another differ substantially from the effects and results of cross-coupling between windings that are in closer proximity to one another. For example, referring to the in-line power supply 20 shown in FIG. 2, the windings 26, 28A, 28B, and 29 are structured and arranged serially along and around the lower flange 24 of the magnetic core 25, rather than around the rungs 21 and 23. As a result, the results of cross-coupling between winding 26 and winding 28A differ from the results of cross-coupling between winding 26 and winding 28B, which differ from the results of cross-coupling between winding 26 and winding 29. This results in varying magnetizing inductances that produce differing phased current ripple and, in some instances, sub-harmonic oscillation of the multiphase power supply 20.
Referring again to FIG. 1, although the distances between the windings 14 and 16 do not vary much, if an additional rung(s) were added to the magnetic core “ladder” 15, the results of cross-coupling between winding 14 and winding 16 would differ from the results of cross-coupling between winding 14 and the winding(s) about the additional rung(s). This, too, would result in varying magnetizing inductances that produce differing phased current ripple and, in some instances, sub-harmonic oscillation of the multiphase power supply 10.
Accordingly, it would be desirable to provide means and methods for providing phase-independent coupling between phase currents by structuring and arranging additional windings in the loop.